Grain storage bin



FIG. 1 is a perspective view of the grain storage bin showing first; and second sides thereof; and,

FIG. 2 is a first side view of the grain storage bin of FIG. 1, the second, third and fourth sides having the same appearance as the first side view.

The top portion of the grain storage bin, the legs, the bracing and the hopper opening shown in broken lines form no part of the claimed design. 

CLAIM The ornamental design for a grain storage bin, as shown and described. 